Tape under frame for lead frame IC package assembly

ABSTRACT

A semiconductor integrated circuit device, and method of manufacturing the same, having a conventional-type lead frame with the die paddle removed. In particular, the die paddle is replaced with a section of tape that is supported by the ends of the lead fingers. The semiconductor die is attached to the tape so that it may be wire bonded to the lead fingers. The tape contains at least one slot to allow for expansion and/or contraction of the tape due to various temperatures experienced during the manufacturing process so that the tape does not wrinkle or warp to alter the position of the die.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of application Ser. No.09/820,999, filed Mar. 29, 2001, pending, which is a continuation ofapplication Ser. No. 09/537,134, filed Mar. 29, 2000, now U.S. Pat. No.6,215,177, issued Apr. 10, 2001, which is a continuation of applicationSer. No. 09/038,858, filed Mar. 11, 1998, now U.S. Pat. No. 6,091,133,issued on Jul. 18, 2000, which continuation of application Ser. No.08/618,359, filed Mar. 19, 1996, now U.S. Pat. No. 5,729,049, issuedMar. 17, 1998.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention relates generally to semiconductor integratedcircuit (IC) devices, and, more specifically, to a method and apparatusfor a semiconductor device utilizing a conventional-type lead frame withno die paddle and having a section of tape to support the semiconductordie.

[0004] 2. State of the Art

[0005] The semiconductor industry has become one of the most competitiveindustries in the world. It is thus essential for manufacturers tominimize the per unit production cost while simultaneously increasingthe number of units manufactured. Because of the high volume ofmanufactured products associated with semiconductor fabrication, smallchanges in production throughput times per semiconductor device can makedramatic changes in the number of devices produced. Moreover, decreasingthe number of defective devices produced, even by a small amount, canhave a similar dramatic effect on the overall production rate.

[0006] One method of semiconductor device construction that has beenrecognized is to use an adhering member to retain the lead fingers of alead frame having a semiconductor support therewith during the wirebonding operation of leads between the semiconductor device and eachlead finger. Such methods and semiconductor devices are illustrated inU.S. Pat. Nos. 4,835,120, 4,891,687, 5,227,662, 5,352,633, and5,475,918.

[0007] Another method of semiconductor device construction that has beenrecognized is the lead-over-chip (LOC) configuration. In thisconfiguration, the lead frame has no semiconductor paddle support as apart thereof. Rather, the semiconductor device is supported in relationto the lead frame and its lead fingers by means of adhesive tapesecuring the semiconductor device to the lead fingers overlaying thesemiconductor device during wire bonding and other operations. TypicalLOC type methods and semiconductor devices are illustrated in U.S. Pat.Nos. 4,862,245, 5,252,853, 5,304,842, and 5,471,369.

[0008] The manufacturing advantages of having a paddleless,conventional-type lead frame have also been recognized in the art. Forexample, as illustrated in U.S. Pat. No. 5,140,404 (“the '404 patent”),assigned to the assignee of the present invention, the die paddle isreplaced with tape. The tape is attached to the underside of the leadfingers and extends over the portion of the lead frame where the diepaddle would normally be located. The tape serves at least twofunctions. First, it provides a platform to support the semiconductordie, and second, it stabilizes the ends of the lead fingers during thewire bonding operation. Moreover, because the tape is attached to oneside of the lead frame, it provides substantially the same downset tolower the die relative to the top surface of the lead fingers. Thus, thesemiconductor die is attached to and supported by the tape during wirebonding of the contacts of the die to the lead fingers.

[0009] However, rather than use thermosetting adhesives to attach thelead fingers of the lead frame to the tape and the semiconductor, as inthe process illustrated in the '404 patent, one or more thermoplasticlayers are applied to a tape which is subsequently used to support thesemiconductor device in a conventional-type lead frame having nosemiconductor support paddle therewith. The lead fingers of the leadframe are bonded to the semiconductor device during the wire bondingoperation. Use of one or more thermoplastic layers on a tape to supportthe semiconductor device as well as lock the lead fingers of the leadframe in place is used in place of typical adhesives which requiresubsequent oven curing steps, such use of thermoplastic layers requiresthe substantially simultaneous bonding of both the semiconductor deviceand the lead fingers of the lead frame to the tape while thethermoplastic remains in its soft state. Furthermore, since thethermoplastic typically melts at 100 degrees Centigrade and the wirebonding of the lead fingers to the semiconductor device occurs when bothare heated to approximately 250 degrees Centigrade, the thermoplasticmay soften during the wire bonding process, thereby allowing thesemiconductor device and/or lead fingers to move, causing bondingproblems.

[0010] When the lead frame is being manufactured, if the lead fingers ofa lead frame have been locked in place through the use of thermosettingtypes of adhesives, rather than thermoplastic types of adhesive asdescribed in the '404 patent, subsequently, it is easier to use athermosetting type of adhesive to attach the semiconductor device on thetape in the paddleless lead frame as conventional semiconductorprocessing is capable of such adhesive use and curing withoutmodification to the fabrication process.

[0011] From the foregoing, it has been recognized in the art to increasechip production efficiency while simultaneously decreasing the number ofdefective products, it is desirable to utilize a conventional-type leadframe without a die paddle and use tape to retain the chip in the leadframe as well as to retain the lead fingers of the lead frame duringwire bonding operations.

[0012] In a conventional-type lead frame, the lead fingers, which formthe leads of the packaged semiconductor device, inwardly extend towardthe center of the lead frame. A die paddle is positioned proximate thetips or proximal ends of the lead fingers and is generally rectangularin shape. The die paddle provides a relatively stable base to mount thesemiconductor die and keep the semiconductor die in place during variousmanufacturing operations where die alignment is crucial, such as wirebonding.

[0013] The die paddle is typically positioned on a lower plane than theplane defined by the lead fingers such that when the semiconductor dieis attached to the die paddle in this configuration, the lowered diepaddle decreases the angle and length of wire necessary to wire bond thecontacts of the semiconductor die to the ends of the lead fingers.Having the die paddle on a lower plane is more difficult to manufactureand may create various handling problems during the manufacturingprocess. For example, modified or alternate fixtures for handling leadframes with a lowered die paddle, as opposed to lead frames where thedie paddle is not lowered, may be necessary. Additionally, the ends ofthe lead fingers that are wire bonded are typically plated with gold orsilver. Plating part of the die paddle is also necessary if a down bondis needed to secure the semiconductor die to the die paddle.

[0014] During the wire bonding operation, the lead frame, along with itsattached die, is typically placed on a heating block to heat the leadframe and die to a specific temperature. Typically, the heating blockheats the semiconductor device to approximately 250 degrees Centigrade.Accordingly, any type of tape used to support the die to the lead frame,as previously discussed, must be capable of withstanding temperatures ofapproximately 250 degrees Centigrade without melting and/or distortingfrom expansion. If the tape does warp or wrinkle from the heat, thesemiconductor die may move relative to the lead fingers and/or the leadfingers may move relative to the semiconductor die. Any such movementmay cause misalignment of the lead fingers in relation to the diecontacts during the wire bonding operation, resulting in improper wirebonding and production of a defective semiconductor device. Moreover, ifthe wire bonding operation successfully wire bonds each of the diecontacts to the lead fingers, cooling of warped or wrinkled tape maycause the die to pull apart the wire bonds. Thus, it would beadvantageous to provide a tape supported lead frame for die attachmentthat also addresses the effects of expansion and/or contraction of thetape used to support the semiconductor die. It would also beadvantageous to provide a tape supported lead frame for die attachmentthat further addresses the effects of attaching the die through the useof thermosetting adhesives, rather than thermoplastic adhesives whichare soft when the die is attached or may soften during the wire bondingprocess, thereby allowing the die or lead fingers to move with respectto each other.

BRIEF SUMMARY OF THE INVENTION

[0015] According to the present invention, a conventional-type,paddleless lead frame is provided having at least one piece of tapeextending to and between the lead fingers where a die paddle wouldnormally lie in a conventional-type lead frame. The tape is of agenerally rectangular configuration, but may also be in the form of acircle, oval, parallelogram or any other shape that would fit within thefootprint defined by the outside edge of packaging encapsulant. Asemiconductor die is then attached to the tape between the proximal endsof the lead fingers using thermosetting types of adhesives. The leadfingers are also attached to the tape through the use of thermosettingtypes of adhesives.

[0016] In a preferred embodiment, the piece of tape has at least oneslot formed therein to allow the tape to expand and contract as it isheated and cooled without moving the semiconductor die attached thereto.Also, the slot permits improved adhesion of the lead fingers and thesemiconductor die to the tape during heating and cooling.

[0017] In another preferred embodiment, the die supporting tape includestwo transversely extending, substantially parallel slots. The two slotsextend along opposite sides of the tape and are proximate the proximalends of some of the lead fingers. The two slots may also extend alongeither of the two substantially parallel sides of the tape and may havesubstantially squared or curved ends.

[0018] In yet another preferred embodiment, the tape includes four slotsforming a crossing pattern. The four slots may be substantially parallelto the sides of the tape or extend substantially diagonally across thetape.

[0019] In still another embodiment, the slots are formed from a seriesof apertures that may be of varying or substantially similar shapes andsizes. For example, each slot may be formed of a row of substantiallyrectangular or square apertures extending along two or four sides of thetape. Moreover, the apertures may form a grid-like pattern over asubstantial portion of the tape.

[0020] In yet another preferred embodiment, the die supporting tape iscomprised of at least two pieces of tape with a slot formed by theseparating distance between the pieces of tape. Each piece of tape mayalso have its own opening or slot formed therein to further allow forexpansion or contraction of the tape.

[0021] It is believed that a major aspect of the invention is that thetape used to support the die can accommodate a certain amount ofexpansion and/or contraction from heating or cooling by including anaperture therein without disturbing the alignment of the semiconductordie. This can be accomplished by having an aperture formed into the tapeitself or using a number of pieces of tape with openings formed inbetween the pieces. These, and other features of the present invention,will become apparent from the following detailed description, theaccompanying drawings, and the appended claims.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0022]FIG. 1 is a schematic top view of a semiconductor integratedcircuit device in accordance with the present invention including afirst embodiment of a tape segment;

[0023]FIG. 2 is a schematic side view of the semiconductor integratedcircuit device of FIG. 1;

[0024]FIG. 3 is a close-up partial top view of the lead fingers and tapeconfiguration of FIG. 1 without an associated semiconductor die;

[0025]FIG. 4 is a close-up partial top view of a second embodiment ofthe lead fingers and tape configuration in accordance with the presentinvention;

[0026]FIG. 5 is a close-up partial top view of a third embodiment of thelead fingers and tape configuration in accordance with the presentinvention;

[0027]FIG. 6 is a close-up partial top view of a fourth embodiment ofthe lead fingers and tape configuration in accordance with the presentinvention;

[0028]FIG. 7 is a close-up partial top view of a fifth embodiment of thelead fingers and tape configuration in accordance with the presentinvention;

[0029]FIG. 8 is a close-up partial top view of a sixth embodiment of thelead fingers and tape configuration in accordance with the presentinvention;

[0030]FIG. 9 is a close-up partial top view of a seventh embodiment ofthe lead fingers and tape configuration in accordance with the presentinvention;

[0031]FIG. 10 is a close-up partial top view of an eighth embodiment ofthe lead fingers and tape configuration in accordance with the presentinvention; and

[0032]FIG. 11 is a close-up partial top view of a ninth embodiment ofthe lead fingers and tape configuration in accordance with the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

[0033] Referring to FIG. 1, a semiconductor integrated circuit (IC)device 10 is shown including a portion of a conventional-type lead frame12. Typically, the lead frame 12 is part of a lead frame strip comprisedof a plurality of lead frames extending from broken edges 13 and 15 andare repeated about the slits 17. The lead frame 12 includes a pluralityof lead fingers 18 that extend toward the center of the lead frame 12.Each of the lead fingers 18 includes a lead end 20 at a proximal endthat is wire bonded to the semiconductor die 14 by wire bond 22.Typically, the lead ends 20 are plated to achieve a sufficient bondbetween the wire bond 22 and the lead end 20. The plated area isgenerally indicated by dashed line 24.

[0034] As should be recognized, the lead frame 12 does not include a diepaddle for supporting the semiconductor die 14. Rather, thesemiconductor die 14 is supported by tape 16. As better seen in FIG. 2,the tape 16 is attached to the bottom surface 26 of the lead frame 12preferably using a thermosetting type of adhesive. When a semiconductordie 14 is subsequently attached to the tape 16, preferably using athermosetting type of adhesive, the die 14 sits down inside the leadframe 12. In this manner, the length of a wire bond 22 between the die14 and the lead finger 18 is decreased because the top surface 28 of thedie 14 is positioned closer to the top surface 30 of the lead frame 12,as opposed to a die attached to the top surface of a lead frame having adie paddle that is not lowered. The preferred type of adhesive used tobond the lead fingers 18 of the lead frame 12 and the semiconductor die14 to the tape 16 may be selected from the group of epoxies, acrylics,silicones and polyamides, such adhesives being thermosetting, i.e.,capable of irreversibly polymerizing and setting or hardening whenheated to some appropriate temperature. Such adhesives are not athermoplastic; i.e., a material that can be repeatedly melted orsoftened by heat without a change of properties. When such adhesives areused to bond the lead fingers 18 of the lead frame 12 to the tape 16,since the adhesive must be cured, typically in an oven, it is necessaryto bond the lead fingers 18 to the tape 16 before bonding thesemiconductor die 14 to the tape 16. In this manner, the lead fingers 18of the lead frame 12 are fixed or locked in position by the tape 16 withthe semiconductor die 14 being subsequently locked in position on thetape 16 with respect to the lead fingers 18. While the lead fingers 18may engage the tape 16 over any desired length thereof, the tape 16preferably engages the lead fingers 18 over a length of at least 0.005inches and may be in excess of 0.060 inches.

[0035] Referring again to FIG. 1, the tape 16 includes two slots 32 and34 transversely extending across the tape 16 proximate a number of leadends 20. As shown, the ends 36 and 38 of the die 14 extend into theslots 32 and 34, respectively. The slots 32 and 34 may, however, beentirely outside or inside the footprint of the die 14. Moreover, theslots 32 and 34 are longer than the corresponding width of the die.However, the slots 32 and 34 may be shorter or longer, depending on thesize of the die used and/or the desires of the manufacturer.

[0036] As shown in FIG. 3, the slots 32 and 34 may transverse the shortside 40 of the tape 16 and have a generally rectangular configuration.Similarly, the slots 42 and 44 shown in FIG. 4 may transverse the longside 46 of the tape 16 and have rounded ends 48, 50 and 52, 54,respectively.

[0037] It may, however, not be necessary to incorporate more than oneslot in the tape 16 to achieve the necessary give in the tape 16 toallow for expansion and/or contraction of the tape 16. For example inFIG. 5, a single slot 56 may transverse the tape 16 about the centerline 58. Moreover, as shown in FIG. 6, the slot or opening 60 mayactually be formed by spacing apart two tape segments 62 and 64. Inaddition, each segment of tape 62 and 64 may each include their owntransverse apertures 66 and 68, respectively, positioned proximateseveral proximate ends 70 of the lead fingers 18.

[0038] It may also be desirable to incorporate more than two slots andposition the slots so that they are not substantially parallel to oneanother. For example in FIG. 7, the slots 72, 74, 76, and 78 aresubstantially diagonally positioned across the tape 16 to form an “X”pattern. Likewise, the slots 80, 82, 84, and 86 may form a cross-likepattern in the tape 16, as shown in FIG. 8.

[0039] Referring now to FIG. 9, each slot may be formed from a pluralityof apertures 88 positioned to form any of the previously describedconfigurations or any other configuration as desired. In thisembodiment, the apertures are configured similar to the embodiment shownin FIG. 3, but may be altered in size, shape, and/or number.

[0040] As shown in FIG. 10, the apertures may include both relativelysmaller apertures 90 and larger apertures 92 and may be positionedproximate the perimeter 94 of the tape 16.

[0041] Finally, as shown in FIG. 11, it may be desirable to form agrid-like pattern of slots or apertures 96 over a substantial portion ofthe tape 16. The apertures 96 may be all substantially the same size orvarying in size as illustrated.

[0042] In the exemplary embodiments, the tape as illustrated has agenerally rectangular configuration, and the illustrated slotconfigurations are generally symmetrical about one lead frame axis oranother. Those skilled in the art, however, will appreciate that thesize and/or shape of the tape may vary and the slots may equally beasymmetrically positioned about the tape without departing from thespirit of the present invention. It will also be appreciated by one ofordinary skill in the art that one or more features of the illustratedembodiments may be combined with one or more features from another toform yet another combination within the scope of the invention asdescribed and claimed herein. Thus, while certain representativeembodiments and details have been shown for purposes of illustrating theinvention, it will be apparent to those skilled in the art that variouschanges in the invention disclosed herein may be made without departingfrom the scope of the invention, which is defined in the appendedclaims. For example, various slot configurations may be utilized; thenumber of apertures may be increased or decreased; and the number oftape segments may be varied.

What is claimed is:
 1. A lead frame assembly for a semiconductor deviceassembly comprising: a lead frame including a periphery, a centralportion, a center axis and a plurality of lead fingers, each lead fingerof the plurality of lead fingers having an inwardly extending enddefining a semiconductor device opening in the lead frame, the leadframe having no die paddle for supporting a semiconductor devicethereon; and a substantially rectangular section of tape having aperipheral portion and a central portion, the section of tape attachedadjacent the peripheral portion to at least a portion of the inwardlyextending ends of the plurality of lead fingers of the conventional leadframe by substantially bonding the plurality of lead fingers to thesection of tape using a thermosetting adhesive said section of the tapehaving at least two slots formed therethrough.
 2. The lead frameassembly of claim 1, wherein said at least two slots include at leasttwo slots transversely extending across a portion of the section oftape.
 3. The lead frame assembly of claim 1, wherein said at least twoslots include at least two slots longitudinally extending across aportion of the section of tape.
 4. The lead frame assembly of claim 2,wherein a first slot of said at least two slots is adjacent a firstportion of the inwardly extending ends of the plurality of lead fingersand a second slot of said at least two slots is positioned adjacent asecond portion of the inwardly extending ends of the plurality of leadfingers.
 5. The lead frame assembly of claim 1, wherein at least oneslot extends substantially diagonally across the section of tape.
 6. Thelead frame assembly of claim 1, further including: at least one slotextending substantially transversely across the section of tape.
 7. Thelead frame assembly of claim 1, further including: at least one aperturesubstantially forming a grid of apertures in at least a portion of thecentral portion of the section of tape.
 8. The lead frame assembly ofclaim 1, further including a semiconductor device attached to andsupported by the section of tape.
 9. The lead frame assembly of claim 9,wherein the semiconductor device extends over at least a portion of thesection of tape having at least one aperture.
 10. The lead frameassembly of claim 1, wherein the section of tape adhesively attaches toanother portion of the plurality of lead fingers.
 11. The lead frameassembly of claim 1, wherein the section of tape is formed from a groupcomprising plastic and polyamide.
 12. The lead frame assembly of claim1, wherein the section of tape can withstand temperatures ofsubstantially at least 250 degrees Centigrade.
 13. The lead frameassembly of claim 1, wherein the section of tape covers at least 0.005inches of the at least a portion of the inwardly extending ends of aportion of the plurality of lead fingers.
 14. A lead frame assembly fora at least one semiconductor device assembly comprising: a lead frameincluding a periphery, a central portion, a center axis and a pluralityof lead fingers, each lead finger having an inwardly extending enddefining a semiconductor device opening in the lead frame, the leadframe having no die paddle for supporting a semiconductor devicethereon; and a substantially rectangular section of tape having at leasttwo apertures formed therethrough, the section of tape attached adjacenta periphery thereof to at least a portion of the inwardly extending endsof the plurality of lead fingers.
 15. The lead frame assembly of claim14, wherein said at least two slots include at least two slotstransversely extending across a portion of the section of tape.
 16. Thelead frame assembly of claim 14, wherein said at least two slots includeat least two slots longitudinally extending across a portion of thesection of tape.
 17. The lead frame assembly of claim 15, wherein afirst slot of said at least two slots is positioned adjacent firstportion of the inwardly extending ends of the plurality of lead fingersand a second slot of said at least two slots is positioned adjacent asecond portion of the inwardly extending ends of the plurality of leadfingers.
 18. The lead frame assembly of claim 14, wherein the section oftape has at least one slot extending substantially diagonally across thesection of tape.
 19. The lead frame assembly of claim 15, wherein the atleast one slot extends substantially transversely across the section oftape.
 20. The lead frame assembly of claim 15, wherein the at least oneaperture substantially forms a grid of apertures in the section of tapein at least a portion of the semiconductor device opening.
 21. The leadframe assembly of claim 14, further including a semiconductor deviceattached to and supported by the section of tape.
 22. The lead frameassembly of claim 15, wherein a semiconductor device substantiallyextends over at least a portion of at least one slot.
 23. The lead frameassembly of claim 14, wherein the section of tape adhesively attaches toanother portion of the plurality of lead fingers.
 24. The lead frameassembly of claim 14, wherein the section of tape is formed from a groupcomprising plastic and polyamide.
 25. The lead frame assembly of claim14, wherein the section of tape can withstand temperatures ofsubstantially at least 250 degrees Centigrade.
 26. The lead frameassembly of claim 14, wherein the section of tape substantially coversat least 0.005 inches of the at least a portion of the inwardlyextending ends of the lead fingers.